I find it strange that they've moved to all-caps for menu titles (FILE, EDIT, VIEW...), especially considering Microsoft's recent uses of good typography.
All-caps is a tradeoff where you take away the identifiable shape of a word to make it draw more attention. You could argue that menu titles would be the absolute worst place to use all-caps.
The ALL CAPS MENU TITLES are supposedly "more Metro-like", even though many Metro screenshots are all-lowercase and the Metro motto is "content before chrome."
I'm surprised Microsoft hasn't made their menu titles disappear until you move the mouse near them (like Mac OS X's X-+ window buttons). That sounds like the "hide the UI so it looks good but is less usable" style Microsoft likes.
There's an extension[1] that does this. I'm now tempted to install it, at least until I find a way to back out the SCREAMING new menus. With that said, I've been using the beta for a couple months and it seems both snappier and more stable than 2010.
I installed the beta, which had all-caps in some of the headers. Initially I was annoyed that Microsoft has to spend so much time on changing the look of every edition of visual studio, but when I ran it, I actually liked the grey colour and the ALL CAPS.
Yes, FILE is less identifiable than file. All the letters are the same height and have similar shapes with all-caps, whereas lowercase letters have more variety and your brain can recognise the shape of words rather than looking at every single letter.
The Wikipedia page for word recognition has some useful links:
All-caps is a tradeoff where you take away the identifiable shape of a word to make it draw more attention. You could argue that menu titles would be the absolute worst place to use all-caps.